Xircom Inc., which makes communications cards to connect laptop computers to networks and cell phones, said fiscal second-quarter earnings will fail to meet forecasts. The news sent its shares down 10%. The Thousand Oaks-based company, citing year 2000 fears of a slowdown in sales, said it expects to report profit of 30 cents to 35 cents a share, before goodwill and other acquisition-related costs, in the quarter ending March 31. Analysts had forecast earnings of 56 cents, according to First Call/Thomson Financial. Xircom said sales of its access cards slowed in the first half of the quarter but have since picked up. Second-quarter revenue will be $108 million to $110 million, Xircom said, also below analysts' expectations. Xircom plans to report second-quarter results April 17. It posted net income of $10.8 million, or 42 cents a share, on sales of $97.7 million in the year-ago period. Xircom shares fell $4.19 to close at $36.81 on Nasdaq. The shares have fallen about 51% this year.